|June 15, 2007, 09:37||
Hi FOAMers, I would like to
Join Date: Mar 2009
Posts: 24Rep Power: 8
I would like to have your opinion about the following problem:
- the strain tensor is defined as
S = 2 * symm(grad(U)) = grad(U) + grad(U)^T (1)
- and, according to the linear algebra, its magnitude is
|S| = sqrt(.5 * (S_ij * S_ij)) (2)
- now, if I let OpenFOAM to write out both the U gradients and S
S = mag(2*symm(fvc:grad(U))) (3)
I see that values coming from (3) and (2) (calculated manually) are different.
I had a look to the vectorSpace class and what I can understand (with my little C++ knowledge), is that the magnitude of a tensor S is given by
|S| = sqrt(Sij * Sij) (4)
which differs from Eq. (2). Additionally, a manual check with the help of Eq.(4) does not return what is given by OF (Eq. (3)) and there is not any constant factor between their values...
What am I missing?
Thanks a lot,
|August 7, 2011, 03:02||
Join Date: Aug 2009
Location: Wiesbaden, Germany
Posts: 241Rep Power: 9
strain rate Tensor is defined by
S:=1/2 [ grad(U)+gard(U)^T]
Try it and give me respond if it's worked.
|Thread||Thread Starter||Forum||Replies||Last Post|
|strain rate in UDF||Paulina||FLUENT||11||November 20, 2014 04:06|
|Vorticity magnitude||CFD-junior||Main CFD Forum||4||August 17, 2011 10:07|
|Rate of Strain Tensor from ANSYS FLOTRAN||H Mayer||Main CFD Forum||0||June 27, 2005 11:56|
|About the rotation and strain tensor||maximus||Main CFD Forum||2||March 6, 2005 05:18|
|second invariant of rate-of-strain tensor||Chun Min Chew||Main CFD Forum||3||December 10, 2003 12:34|